The present invention relates generally to intra-aortic balloon (hereinafter "IAB") assemblies, and more particularly, to an improved IAB assembly and percutaneous method for inserting same employing a new hemostasis device to facilitate insertion of the IAB into the body by (1) reducing insertion time, and (2) by lowering the degree of obstruction in the femoral artery, while at the same time controlling bleeding back through the insertion site.
IAB devices are introduced into the body and are used to assist the pumping action of the heart. See, for example, U.S. Pat. No. 4,362,150. In some instances, they may remain in the body for extended periods of time, such as several days or more.
One method of installing an IAB device in the body is via non-surgical insertion into the femoral common artery using the percutaneous "Seldinger" insertion technique. In the Seldinger technique, the skin is punctured with a hypodermic needle to form a hole through the skin and into the femoral artery. A first guide wire is inserted through the needle into the femoral artery and the needle is then removed from the artery, leaving the guide wire in place. The puncture hole created by the needle is then expanded by an inserter dilator (for example, an 8-French dilator) which slides over the guide wire through the skin and into the artery. The inserter dilator is then removed and a series of progressively larger dilators are inserted into the hole over the guide wire to increase the size of the hole. Next, an insertion sheath is passed through the hole over the guide wire and into the femoral artery. This sheath has an inside diameter generally corresponding to the outside diameter of the IAB to be inserted. The first guide wire is removed and replaced by a second guide wire which is fed up through the artery to the vicinity of the aortic arch. The IAB is passed over this second guide wire and slides up through the insertion sheath and along the artery to a point just below the aortic arch.
Although the foregoing procedure generally is a safe, rapid and efficacious way of intra-aortic balloon insertion, the prerequisite insertion of the sheath requires time and equipment to perform, often under circumstances such that time is a critical factor to patient survival, as during cardiogenic shock. During the foregoing procedure, arterial bleeding through the insertion sheath must be carefully controlled during the time interval between the removal of the first guide wire from the sheath and the insertion of the wrapped balloon containing the second guide wire. Often, especially in a hypovolemic patient, this loss of blood may be critical.
Moreover, when the balloon bladder is wrapped around the central cannula, spiral interstices are produced along its length. The interstices of the wrapped balloon membrane do not provide for the complete occlusion of the insertion sheath between its inner wall and the wrapped balloon. Therefore, a certain amount of arterial bleeding takes place during the time that is required to fully insert the wrapped balloon membrane portion of the balloon catheter into the blood vessel. In some cases, the insertion sheath may have to be withdrawn partly from the percutaneous wound to permit complete introduction of the balloon membrane into the sheath, especially in those cases of extreme vascular tortuosity. This creates an additional loss of critical time and of critical blood.
Another problem experienced with some patients is that after IAB insertion is complete, blood flow to the lower extremities is diminished substantially. The decrease in blood flow is generally attributable to the obstruction of the femoral artery caused by the relatively large diameter of the insertion sheath extending into the artery. By removing the sheath, the obstruction in the femoral artery can be decreased substantially. Certain prior art techniques attempt to solve this problem by utilizing splittable ("tear-away") insertion sheaths, such as, for example, those identified in U.S. Pat. Nos. 4,166,469, 4,581,019 and 4,581,025. Once the insertion sheath is removed, however, the arterial wall must constrict to seal around the balloon catheter (which has a smaller outside diameter than the insertion sheath) to prevent bleeding at the insertion site. In non-elastic or diseased vessels, the required vessel constriction may not always occur resulting in profuse bleeding at the insertion site between the IAB catheter and arterial puncture. If bleeding cannot be stopped, the IAB must be removed. One way to stop this bleeding is to exert pressure on the artery above the insertion site. Such an approach, however, adds an additional step to the IAB insertion process, and may also result in damage to the balloon catheter.
In response to the foregoing problems, other approaches have been advanced involving the use of a tapered hemostasis device which is slidably mounted to the balloon catheter, and which can be inserted into the patient after the tear-away sheath is removed to control bleeding at the insertion site. See, for example, the device's identified in my co-pending U.S. patent application Ser. No. 53,183 and Magro et al. U.S. Pat. No. 4,738,658. The subject invention is an improvement over those devices. For example, due to the structure of such devices, a patient having limited or little vessel and skin elasticity will ordinarily require a greater length of the hemostasis device to be inserted to stop bleeding at the IAB puncture site than a patient whose vessels and skin are relatively elastic. As the length and diameter of the hemostasis device inserted increases, there will be an accompanying increase in both insertion time and body resistance to insertion.
Accordingly, it is an object of the present invention to provide a new IAB assembly and method of inserting same into the body which incorporates a new hemostasis device for controlling bleeding at the insertion site after insertion of the IAB. It is another object of the present invention to provide a new IAB assembly including a hemostasis device which can be inserted into the patient using either a tear-away insertion sheath or a sheathless insertion technique.
It is yet a further object of the present invention to provide a new hemostasis device which controls bleeding at the IAB insertion site without restricting good blood flow through the femoral artery to any great degree. It is still another object of the invention to provide a new IAB assembly including a hemostasis device which does not rely on a tapered configuration to perform the hemostasis function.
It is still another object of the invention to provide a new hemostasis device providing a first constant diameter segment at the distal end thereof configured and dimensioned to generate less initial resistance during insertion into the patient's skin, and a second constant diameter segment positioned proximally with respect to the first segment which is dimensioned to fill the opening in the patient's skin created by the insertion of the IAB device, and thereby stop bleeding from the femoral artery at the insertion site.
It is still a further object of the present invention to provide a new hemostasis device including a transition segment connecting the first and second constant diameters segments which allows essentially immediate transition from the first segment to the second segment during insertion of the hemostasis device, yet at the same time minimizes any resistance encountered during insertion of the second larger diameter segment through the patient's skin.
The foregoing specific objects and advantages of the invention are illustrative of those which can be achieved by the present invention and are not intended to be exhaustive or limiting of the possible advantages which can be realized. Thus, these and other objects and advantages of the invention will be apparent from the description herein or can be learned from practicing the invention, both as embodied herein or as modified in view of any variations which may be apparent to those skilled in the art. Accordingly, the present invention resides in the novel parts, constructions, arrangements, combinations and improvement herein shown and described.